In recent years, a turning direction indicator device that flashes on and off turn-signal lamps according to an operation of an operating lever installed in an automobile is demanded to produce a low noise. A large operation noise may be produced in the case that a driver rotates the operating lever in a turning direction and retains it in a position for indicating the turning direction, or the case that the operating lever is automatically returned to a neutral position in accordance with a rotating operation of the steering wheel.
FIGS. 9 and 10 are a partial cutaway view and an exploded perspective view of conventional turning direction indicator device 501, respectively. Turning direction indicator device 501 includes actuator 1 and cover 2 for accommodating actuator 1. Shaft part 1A provided on an upper surface of actuator 1 is pivotally supported by bearing part 2A at a front side lower surface of cover 2, such that actuator 1 is rotatable in rightward and leftward directions.
At a tip of operating lever 3, substantially cylindrical operating part 3A is provided. At a root of operating lever 3, driver part 3B that extends from operating part 3A toward actuator 1 is provided.
Shaft part 3C provided at each side of driver part 3B is pivotally supported by shaft hole 1B provided in a front part of actuator 1, whereby operating lever 3 is attached to actuator 1 so as to be rotatable in upward and downward directions.
Cam body 5 is placed on an upper surface of actuator 1. Cam body 5 includes base part 5A having a substantially elongated circular shape, upper shaft part 5B provided on an upper surface of base part 5A, lower shaft part 5C provided on a lower surface of base part 5A, front cam part 5D projecting from a front part of base part 5A, and rear cam part 5E projecting from a rear part of base part 5A. The upper surface of base part 5A has a flat shape. Lower shaft part 5C extends coaxially with upper shaft part 5B.
Guide groove 2B is provided in a lower surface of cover 2. Guide groove 2B has an elongated hole shape extending in frontward and rearward directions, and is concave upward. Upper shaft part 5B engages with guide groove 2B, whereby cam body 5 is retained with cover 2 so as to be capable of shifting in the frontward and rearward directions and rotating.
Grease is applied between an upper surface of cam body 5 and the lower surface of cover 2, to reduce the sliding friction between the lower surface of cover 2 and the upper surface of cam body 5. Further, resistance due to, e.g. viscosity of the grease suppresses a rapid movement of cam body 5.
Both ends of urging spring 6, a coil spring, are engaged at predetermined positions on the lower surface of cover 2. Engaging recess 5F is provided in the lower surface of cam body 5. The substantially center part of urging spring 6 engages with engaging recess 5F of cam body 5, to urge cam body 5 in the rearward direction.
Release element 7 has release projecting parts 7A that project from opposite ends of release element 7 in the rearward direction, to form a substantially squared C-shape. Release element 7 is retained substantially at the middle of the upper surface of actuator 1.
Hole 1F provided in a rear end part of actuator 1 accommodates click spring 9A together with click pin 9B therein while click spring 9A is compressed. Click pin 9B faces click cam 2D of cover 2. Click pin 9B elastically contacts click cam 2D. Click spring 9A and click pin 9B constitute retainer unit 9 that retains actuator 1 at the neutral position of operating lever 3. When operating lever 3 rotates in rightward and leftward directions, retainer unit 9 operates while giving a click feel, and retains actuator 1 at predetermined positions in the rightward and leftward directions.
Case 10 opens upward. Case 10 pivotally supports actuator 1 such that actuator 1 is rotatable about shaft part 1A. Further, case 10 covers an opening of cover 2 that opens downward, to accommodate actuator 1 having operating lever 3 attached thereto.
Wiring patterns are formed on upper and lower surfaces of wiring board 11 made of an insulating resin. An upper end of slider 12 engages with driver recess 1G of actuator 1. A fixed contact is disposed at a predetermined place on wiring board 11. Switch contact part 12A is structured, in which movable contact 12B fixed to the lower surface of slider 12 slides on the fixed contact while elastically contacting thereto to perform electrical connection and disconnection between movable contact 12B and the fixed contact.
Rotation of actuator 1 associated with a rightward or leftward rotary operation of operating lever 3 causes electrical connection and disconnection of switch contact part 12A. Bottom plate 13 covers the lower surface of wiring board 11, to structure turning direction indicator device 501.
FIGS. 11A and 11B are top schematic views of turning direction indicator device 501 for illustrating an operation of turning direction indicator device 501. Turning direction indicator device 501 is installed below the steering wheel located in front of a driver's seat in an automobile, such that operating part 3A projects outward. As shown in FIG. 11A, substantially arcuate cancel cams 20 rotate in accordance with the rotation of the steering shaft. Cancel cams 20 are disposed near the rear side of actuator 1. Rear cam part 5E of cam body 5 projects outward from opening 2C (see FIG. 10) of cover 2. A lead wire for external connection is connected to connector part 11A of wiring board 11, and connects switch contact part 12A electrically to an electronic circuit of the automobile. Retainer cam 1E has a substantially triangular shape having an apex and opposite end parts.
As shown in FIG. 11A, when operating lever 3 is retained at the neutral position, cam body 5 is urged by urging spring 6 in the rearward direction, which is directed toward cancel cam 20. Here, lower shaft part 5C elastically contacts the apex of retainer cam 1E, and rear cam part 5E is at a non-abutting position which is outwardly away from a rotary orbit of cancel cams 20. Here, front cam part 5D is at substantially the intermediate position between release projecting parts 7A positioned at the opposite ends of release element 7.
When the driver rotates operating lever 3 in the rightward direction upon turning the automobile rightward, as shown in FIG. 11B, operating lever 3 rotates with actuator 1 about shaft part 1A of actuator 1. Actuator 1 is retained by retainer unit 9 (see FIG. 10) at a first operational position where actuator 1 has rotated rightward by a predetermined angle. Here, lower shaft part 5C of cam body 5 slides on an angled edge of retainer cam 1E from the apex while maintaining elastic contact, to approach one of the opposite end parts of retainer cam 1E.
Similarly, when operating lever 3 is rotated in the leftward direction, actuator 1 is retained by retainer unit 9 (see FIG. 10) at a second operational position where actuator 1 has rotated in the leftward direction by a predetermined angle. Here, lower shaft part 5C of cam body 5 slides on the angled edge of retainer cam 1E from the apex while maintaining elastic contact, to approach the other one of the opposite end parts of retainer cam 1E.
When actuator 1 is retained at the first operational position, rear cam part 5E of cam body 5 recedes to be positioned on the rotary orbit of cancel cams 20, i.e., an abuttable position, and a tip of front cam part 5D abuts on an inner side surface of release projecting part 7A.
In accordance with the rotation of actuator 1, switch contact part 12A performs electrical connection and disconnection to produce an electric signal, based on which the electronic circuit of the automobile flashes on and off a right turn-signal lamp of the automobile.
Next, when the driver rotates the steering wheel clockwise in the rightward direction for turning the automobile rightward, cancel cams 20 as the steering wheel rotate clockwise. The clockwise rotation of cancel cams 20 causes cancel cam 20 to abut on rear cam part 5E of cam body 5. Then, cam body 5 rotates counterclockwise about upper shaft part 5B. Here, front cam part 5D is removed away from release projecting part 7A, while enhancing the clockwise urging force attributed to bending of urging spring 6 engaged with engaging recess 5F.
Further, as this clockwise rotary operation of the steering wheel further proceeds, rear cam part 5E is removed from cancel cam 20. Thus, clockwise rotation of cam body 5 caused by cancel cam 20 is released. Here, cam body 5 is urged by urging spring 6 so as to rotate clockwise, and front cam part 5D hits the inner side surface of release projecting part 7A positioned on the right side of release element 7.
Grease is applied between the upper surface of cam body 5 and the lower surface of cover 2. The upper surface of base part 5A of cam body 5 slides on the lower surface of cover 2. When used for a long period under various environments in terms of changes in temperature, humidity and the like, the grease between the upper surface of base part 5A of cam body 5 and the lower surface of cover 2 is expelled from the sliding range toward the outside. This reduces the resistance due to the grease exerted over the operation of cam body 5 and causes front cam part 5D to hit release projecting part 7A with a relatively large impact force, which is prone to result in a large hitting noise.
When the driver finishes turning the automobile and is to return the steering wheel to an original neutral position, the steering wheel is rotated in the opposite direction, i.e., the counterclockwise direction. This rotation of the steering wheel in the counterclockwise direction allows cancel cams 20 in the state shown in FIG. 11B to rotate in the counterclockwise direction, whereby cancel cam 20 pushes rear cam part 5E. Thus, cam body 5 rotates in the clockwise direction about upper shaft part 5B. Here, the right end of front cam part 5D rotates actuator 1 in the counterclockwise direction. Thus, as shown in FIG. 11A, the neutral state is recovered in which actuator 1 and operating lever 3 return to the neutral position and retained there, and the turn-signal lamp having been flashing on and off is turned off.
A turning direction indicator device similar to conventional turning direction indicator device 501 is disclosed in Japanese Patent Laid-Open Publication No. 08-167345.